Resin binder compositions

ABSTRACT

A resin binder composition comprising: (1) a synthetic resin; (2) a water-soluble, polymeric, carboxylic thickener; and (3) a metal ammine, complex coordination compound capable of releasing ions of said metal to control the total migration of the resin binder during its deposition on a fibrous web.

United States Patent [1 1 Drelich et a1.

[1 11 3,865,765 [451 Feb. 11, 1975 [5 RESIN BINDER COMPOSITIONS [75]Inventors: Arthur H. Drelich, Plainfield; Bobby R. Bowman, EastBrunswick, both of NJ.

[73] Assignee: Johnson and Johnson, New

Brunswick, NJ.

[22] Filed: Dec. 12, 1973 [2]] Appl. No: 424,022

Related U.S. Application Data [60] Division of Ser. No. 176.306, Aug.30, 1971, Pat. No. 3,821,146, which is a continuation-in-part of Ser.No. 109,026, Jan. 22, 1971, Pat. No. 3,706,595.

[52] US. Cl. 260/l7.4 ST, 117/38, 117/44, 117/62, 117/121, 117/140 A,117/161 UL, 260/9 [5 1] llnt. Cl. C08f 45/00, C08g 51/00 [58] Field ofSearch 260/9, 17.4 ST

[56] References Cited UNITED STATES PATENTS 2,758,102 8/1956 Grummi ttet a1 260/17.4 ST x 2,843,553 7/1958 Wenzelbcrger 260/17.4 ST 3,770,67411/1973 Araki et a1. 260/174 ST 3,809,662 5/1974 Araki et al. 260/17.4ST

Primary Examiner-Lucille M. Phynes 2 Claims, No Drawings RESIN BINDERCOMPOSITTONS This patent application is a division of co-pending patentapplication, Ser. No. 176,306, filed on Aug. 30, 1971, now U.S. Pat. No.3,821,146, granted June 28, 1974 which in turn is a continuation-in-partof copending patent application, Ser. No. 109,026, filed Jan. 22, 1971,now U.S. Pat. No. 3,706,595 which issued on Dec. 19, 1972.

The present invention relates to porous, absorbent fibrous sheetmaterials and to their methods of manufacture. More particularly, thepresent invention is concerned with the so-called bonded, nonwoven"textile fabrics, i.e., fabrics produced from textile fibers without theuse of conventional spinning, weaving, knitting or felting operations.Although not limited thereto, the invention is of primary importance inconnection with nonwoven fabrics derived from oriented or carded fibrouswebs composed of textile-length fibers, the major proportion of whichare oriented predominantly in one direction.

Typical of such fabrics are the so-called MAS- SLINN nonwoven fabrics,some of which are described in greater particularity in U.S. Pat. Nos.2,705,687 and 2,705,688, issued Apr. 5, 1955, to D. R. Petterson, etal., and l. S. Ness, et al., respectively.

Another aspect of the present invention is its application to nonwovenfabrics wherein the textile-length fibers were originally predominantlyoriented in one direction but have been reorganized and rearranged inpredetermined designs and patterns of fabric openings and fiber bundles.Typical of such latter fabrics are the so-called KEYBAK" bundlednonwoven fabrics, some of which are described in particularity in U.S.Pat. Nos. 2,862,251 and 3,033,721, issued Dec. 2, 1958 and May 8, 1962,respectively, to F. Kalwaites.

Still another aspect of the present invention is its application tononwoven fabrics wherein the textilelength fibers are disposed at randomby air-laying techniques and are not predominantly oriented in any onedirection. Typical nonwoven fabrics made by such procedures are termedisotropic nonwoven fabrics and are described, for example, in U.S. Pat.Nos. 2,676,363 and 2,676,364, issued Apr. 27, 1954, to C. H. Plummer, eta1.

And, still another aspect of the present invention is its application tononwoven fabrics which comprise textile-length fibers and which are madebasically by conventional or modified aqueous papermaking techniquessuch as are described in greater particularity in pending patentapplication Ser. No. 4,405, filed Jan. 20, 1970 by P. R. Glor and A. H.Drelich. Such fabrics are also basically isotropic" and generally havelike properties in all directions.

The conventional base starting material for the majority of thesenonwoven fabrics is usually a fibrous web comprising any of the commontextile-length fibers, or mixtures thereof, the fibers varying inaverage length from approximately one-half inch to about two andone-half inches. Exemplary of such fibers are the natural fibers such ascotton and wool and the synthetic or man-made cellulosic fibers, notablyrayon or regenerated cellulose.

Other textile length fibers ofa synthetic or man-made origin may be usedin various proportions to replace either partially or perhaps evenentirely the previouslynamed fibers. Such other fibers include:polyamide fibers such as nylon 6, nylon 66, nylon 610, etc.; polyesterfibers such as Dacron, Fortrel and Kodel; acrylic fibers such asAcrilan," Orlon" and Creslan; modacrylic fibers such as Verel and Dynel;polyolefinic fibers derived from polyethylene and polypropylene;cellulose ester fibers such as Arnel and Acele; polyvinyl alcoholfibers; etc.

These textile length fibers may be replaced either partially or entirelyby fibers having an average length ofless than about one-half inch anddown to about onequarter inch. These fibers, or mixtures thereof, arecustomarily processed through any suitable textile machinery (e.g., aconventional cotton card, a Rando- Webber," a papermaking machine, orother fibrous web producing apparatus) to form a web or sheet of looselyassociated fibers, weighing from about grains to about 2,000 grains persquare yard or even higher.

If desired, even shorter fibers, such as wood pulp fibers or cottonlinters, may be used in varying proportions, even up to 100%, where suchshorter length fibers can be handled and processed by availableapparatus. Such shorter fibers have lengths less than A inch.

The resulting fibrous web or sheet, regardless of its method ofproduction, is then subjected to at least one of several types ofbonding operations to anchor the individual fibers together to form a.self-sustaining web. One method is to impregnate the fibrous web overits entire surface area with various well-known bonding agents, such asnatural or synthetic resins. Such over-all impregnation produces anonwoven fabric of good longitudinal and cross strength, acceptabledurability and washability, and satisfactory abrasion resistance.However, the nonwoven fabric tends to be somewhat stiff and boardlike,possessing more of the properties and characteristics of paper or boardthan those of a woven or knitted textile fabric. Consequently, althoughsuch over-all impregnated nonwoven fabrics are satisfactory for manyuses, they are still basically unsatisfactory as general purpose textilefabrics.

Another well-known bonding method is to print the fibrous webs withintermittent or continuous straight or wavy lines, or areas ofbinderextending generally transversely or diagonally across the web andadditionally, if desired, along the fibrous web. The resulting nonwovenfabric, as exemplified by a product disclosed in the Goldman U.S. Pat.No. 2,039,312 and sold under the trademark MASSLINN, is far moresatisfactory as a textile fabric than over-all impregnated webs in thatthe softness, drape and hand of the resulting nonwoven fabric morenearly approach those of a woven or knitted textile fabric.

The printing of the resin binder on these nonwoven webs is usually inthe form of relatively narrow lines, or elongated rectangular,triangular or square areas, or annular, circular, or elliptical binderareas which are spaced apart a predetermined distance which, at itsmaximum, is preferably slightly less than the average fiber length ofthe fibers constituting the web. This is based on the theory that theindividual fibers of the fibrous web should be bound together in as fewplaces as possible.

The nominal surface coverage of such binder lines or areas will varywidely depending upon the precise properties and characteristics ofsoftness, drape, hand and strength which are desired in the final bondedproduct. In practice, the nominal surface coverage can be designed sothat it falls within the range of from about to about 50% of the totalsurface of the final product. Within the more commercial aspects of thepresent invention, however, nominal surface coverages of from about 12%to about 40% are preferable.

Such bonding increases the strength of the nonwoven fabric and retainssubstantially complete freedom of movement for the individual fiberswhereby the desirable softness, drape and hand are obtained. Thisspacing of the binder lines and areas has been accepted by the industryand it has been deemed necessarily so, if the stiff and board-likeappearance, drape and hand of the over-all impregnated nonwoven fabricsare to be avoided.

The nonwoven fabrics bonded with such line and area binder patterns havehad the desired softness, drape and hand and have not been undesirablystiff or board-like. However, such nonwoven fabrics have also possessedsome disadvantages.

For example, the relatively narrow binder lines and realtively smallbinder areas of the applicator (usually an engraved print roll) whichare laid down on the fibrous web possess specified physical dimensionsand inter-spatial relationships as they are initially laid down.Unfortunately, after the binder is laid down on the wet fibrous web andbefore it hardens or becomes fixed in position, it tends to spread,diffuse or migrate whereby its physical dimensions are increased and itsinter-spatial relationships decreased. And, at the same time, the binderconcentration in the binder area is lowered and rendered less uniform bythe migration of the binder into adjacent fibrous areas. One of theresults of such migration is to make the surface coverage of the binderareas increase whereby the effect of the intermittent bonding approachesthe effect of the overall bonding. As a result, some of the desiredsoftness, drape and hand are lost and some of the undesired propertiesof harshness, stiffness and boardiness are increased.

Various methods have been proposed to prevent or to at least limit suchspreading, diffusing or migration tendencies of such intermittent bindertechniques.

For example, U.S. Pat. No. 3,009,822, issued Nov. 21, 1961 to A. H.Drelich, et al., discloses the use of a non-migratory regeneratedcellulose viscose binder which is applied in intermittent fashion tofibrous webs under conditions wherein migration is low and theconcentration ofthe binder in the binder area is as high as 35% byweight, based on the weight of the fibers in these binder areas. Suchviscose binder possesses inherently reduced spreading, diffusing andmigrating tendencies, thereby increasing the desired softness, drape andhand of the resulting nonwoven fabric. This viscose binder has foundacceptance in the industry but the use of other more versatile bindershas always been sought.

Resins, or polymers as they are often referred to herein asinterchangeable terms, are high molecular weight organic compounds and,as used herein, are of a synthetic or man-made origin. These syntheticor man-made polymers have a chemical structure which usually can berepresented by a regularly repeating small unit, referred as a mer," andare formed usually either by an addition or a condensationpolymerization of one or more monomers. Examples of addition polymersare the polyvinyl chlorides, the polyvinyl acetates, the polyacrylicresins, the polyolefins, the synthetic rubbers, etc. Examples ofcondensation polymers are the polyurethanes, the polyamides, thepolyesters, etc.

Of all the various techniques employed in carrying out polymerizationreactions, emulsion polymerization is one of the most commonly used.Emulsion polymerized resins, notably polyvinyl chlorides, polyvinylacetates, and polyacrylic resins, are widely used throughout manyindustries. Such resins are generally produced by emulsifying themonomers, stabilizing the monomer emulsion by the use of varioussurfactant systems, and then polymerizing the monomers in the emulsifiedstate to form a stabilized resin polymer. The resin polymer is usuallydispersed in an aqueous medium as discrete particles of colloidaldimensions (1 to 2 microns diameter or smaller) and is generally termedthroughout the industry as a resin dispersion," or a resin emulsion orlatex.

Generally, however, the average particle size in the resin dispersion isin the range of about 0.1 micron (or micrometer) diameter, withindividual particles ranging up to l or 2 microns in diameter andoccasionally up to as high as about 3 or 5 microns in size. The particlesizes of such colloidal resin dispersions vary a great deal, not onlyfrom one resin dispersion to another but even within one resindispersion itself.

The amount of resin binder solids in the resin colloidal aqueousdispersion varies from about 1/10% solids by weight up to about byweight or even higher solids, generally dependent upon the nature of themonomers used, the nature of the resulting polymer resin, the surfactantsystem employed, and the conditions under which the polymerization wascarried out.

These resin colloidal dispersions, or resin emulsions, or latexes, maybe anionic, non-ionic, or even polyionic and stable dispersions areavailable commercially at pHs of from about 2 to about 11.

As will be pointed out in greater detail, such resin dispersions areused in the present inventive concept at alkaline pH ranges. Variousalkaline reagents, such as ammonia, are therefore added to bring the pHout of the acid range.

The amount of resin which is applied to the porous or absorbent materialvaries within relatively wide limits, depending upon the resin itself,the nature and character of the porous or absorbent materials to whichthe resins are being applied, its intended use, etc. A general range offrom about 4% by weight up to about 50% by weight, based on the weightof the porous or absorbent material, is satisfactory under substantiallyall uses. Within the more commercial limits, however, a range of fromabout 10% to about 30% by weight, based on the weight of the porous orabsorbent material, is preferred.

Such resins have found use in the coating industries for the coating ofwoven fabrics, paper and other materials. The resins are also used asadhesives for laminating materials or for bonding fibrous webs. Theseresins have also found wide use as additives in the manufacture ofpaper, the printing industry, the decorative printing of textiles, andin other industries.

In most instances, the resin is colloidally dispersed in water and, whenapplied from the aqueous medium to a porous or absorbent sheet materialwhich contains additional water if carried by the water until the wateris evaporated or otherwise driven off. If it is desired to place theresin only on the surface of the wet porous or absorbent sheet materialand not to have the resin penetrate into the porous or absorbent sheetmaterial, such is usually not possible inasmuch as diffusion takes placebetween the aqueous colloidal resin and the water in the porousmaterial. In this way, the colloidal resin tends to spread into andthroughout the porous material and does not remain merely on itssurface.

Or, if it is desired to deposit the resin in a specific intermittentprint pattern, such as is used in bonding nonwoven fabrics, the aqueouscolloid tends to diffuse and to wick along the individual fibers and tocarry the resin with it beyond the confines of the nominal intermittentprint pattern. As a result, although initially placed on the nonwovenfabric in a specific intermittent print pattern, the ultimate patterngoes far beyond that due to the spreading or migration which takes placedue to the diffusion of the water and the resin, until the water isevaporated or otherwise driven off.

We have discovered new resin binder compositions containing polymerscolloidally dispersed in aqueous media and new methods of applying suchresin binder compositions to porous or absorbent fibrous materials,whereby the resins are applied in a controlled, relatively non-migratingmanner. If it is desired that the resin be placed only on the surface ofthe porous or absorbent material, our compositions and methods willallow this to be done. Furthermore, if it is desired that the resin beimpregnated throughout the material, from one surface to the othersurface, again, our composition and method will allow this to be done.

We have now discovered an improved method of controllably depositingcolloidal resin compositions on porous or absorbent materials wherebyspreading, diffusing, and migration of the resin are controlled and aremarkedly reduced and wherein the concentration of the resin in the resinbinder area reaches exceptionally high values in short distances asmeasured at right angles to the bond edge. When applied to fibrous websin the manufacture of nonwoven fabrics, excellent strength is obtainedin the resulting bonded fabrics along with textile-like softness, handand drape.

The improved method involves the use of a resin dis persion whichcomprises from about 0.1% to about 60% by weight on a solids basis ofacolloidal synthetic resin, from about 0.05% by weight to about 7% byweight, based on the weight of the colloidal synthetic resin solids of awater-soluble, polymeric, carboxylic thickener; and from about 0.0l% byweight to about 5% by weight, based on the weight of the colloidalsynthetic resin solids of a metal ammine complex coordination compoundwherein the central metallic atom is chromium, nickel, zinc, or copper,said colloidal resin dispersion being stable at alkaline pHs in thepresence of an excess of a complexing substance such as ammoniumhydroxide and at certain concentrations or degrees of dilution but whichis unstable at lesser concentrations or greater degrees of dilution whenin the presence of heavy metal ions such as chromium, nickel, zinc, orcopper.

The synthetic resin may be selected from a relatively large group ofsynthetic resins well known in industry for bonding purposes and may beofa self cross-linking type, externally cross-linking type, or notcross-linked. Specific examples of such synthetic resins include:polymers and copolymers of vinyl ethers; vinyl halides such asplasticized and unplasticized polyvinyl chloride, polyvinylchloride-polyvinyl acetate, ethylenevinyl chloride, etc.; polymers andcopolymers of vinyl esters such as plasticized and unplasticizedpolyvinyl acetate, ethylene-vinyl acetate, acrylic-vinyl acetate,

etc.; polymers and copolymers of the polyacrylic resins such as ethylacrylate, methyl acrylate, butyl acrylate, ethylbutyl acrylate, ethylhexyl acrylate, hydroxyethyl acrylate, dimethyl amino ethyl acrylate,etc.; polymers and copolymers of the polymethacrylic resins such asmethyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butylmethacrylate, etc.; polymers and copolymers of acrylonitrile,methacrylonitrile, acrylamide, N-isopropyl acrylamide, N-methylolacrylamide, methacrylamide, etc.; vinylidene polymers and copolymers,such as polyvinylidene chloride, polyvinylidene chloride-vinyl chloride,polyvinylidene chlorideethyl acrylate, polyvinylidene chloride-vinylchlorideacrylonitrile, etc.; polymers and copolymers of polyolefinicresins including polyethylene, polypropylene, ethylene-vinyl chlorideand ethylene-vinyl acetate which have been listed previously; thesynthetic rubbers such as l,2-butadiene, 1,3-butadiene, 2-ethyl-l,3-butadiene, high, medium and carboxylated butadieneacrylonitrile,butadiene-styrene, chlorinated rubber, etc., natural latex; thepolyurethanes; the polyamides; the polyesters; the polymers andcopolymers of the my renes including styrene, Z-methyl styrene, 3-methylstyrene, 4-methyl styrene, 4-ethyl styrene, 4-butyl styrene; naturallatex; phenolic emulsions; etc.

These resins may be used either as homopolymers comprising a singlerepeating monomer unit, or they may be used as copolymers comprisingtwo, three, or more different monomer units which are arranged in randomfashion, or in a definite ordered alternating fashion, within thepolymer chain. Also included within the inventive concept are the blockpolymers comprising relatively long blocks of different monomer units ina polymer chain and graft polymers comprising chains of one monomerattached to the backbone of another polymer chain.

As pointed out previously, the compositions and formulations containingthese polymers must be stable at an alkaline pH range of from about 7 toabout 10 /2 or even higher which is the range wherein they are utilized,with preferred pH ranges extending from about 7%. to about 10. Suchstability is particularly required for these polymer dispersions, whenexisting at their normal concentration levels in the presence ofwatersoluble polymeric carboxylic thickeners, and metal ammine complexcoordination compounds, as described herein.

The water soluble polymeric carboxylic thickener may be selected from arelatively large group of such materials which include, for example:polyacrylic-acid; polymeric crotonic acid; copolymers of vinyl acetateand crotonic acid; copolymers of vinyl acetate and acrylic acid;polyacrylic acid-polyacrylamide copolymers; polymethacrylic acid;polymethacrylic acidpolyacrylamide copolymers; carboxymethyl cellulose;carboxyethyl cellulose; carboxypropyl cellulose; polycarboxymethylhydroxyethyl cellulose; alginic acid; polymers of acrylic acid andacrylic acid esters; polymers of ozB-unsaturated carboxylic acids suchas he conic acid; etc. These water soluble, polymeric, carboxylicthickeners may be used in their acid forms but normally it is preferredto use their water soluble neutralized salts, that is, their sodium,potassium, lithium, ammonium, or like water soluble salts.

To the emulsion polymerized composition containing the colloidal resinis added a small amount of from about 0.01% by weight to about 5% byweight, based on the weight of the synthetic resin solids, of a metalammine complex coordination compound wherein the central metallic atomis chromium, nickel, zinc, or copper.

Examples of metal ammine complex coordination compounds are:

hexammine chromium chloride :1)6] a' 2 pentammine chloro chromiumchloride [Cr(NH Cl]Cl hexammine nickel chloride hexammine nickel bromidehexammine nickel chlorate hexammine nickel iodide hexammine nickelnitrate tetrammine zinc carbonate tetrammine zinc sulfate diammine zincchloride tetrammine zinc chloride diammine copper acetate I tetramminecopper sulfate [Cu(NH ]SO .l-l O tetrammine copper hydroxide The metalammine complex coordination compound is normally prepared by chemicalreaction between a soluble salt of the metal, such as, for example, zincchloride, with an excess of concentrated ammonium hydroxide, whereby themetal ammine complex coordination compound, such as, for example, zinctetrammine chloride, is formed.

The zinc chloride, preferably in an aqueous 70-72% solution, is slowlydripped into the concentrated ammonium hydroxide (28% NH;,), withstirring, while the solution is surrounded by cooling water. The zinctetrammine chloride forms at once.

The amount of excess ammonium hydroxide should be sufficient toestablish and maintain a pH range of from about 7 to about 10 /z, andpreferably from about 7 Bi to about l0, during preparation of the metalammine complex coordination compound and during its formulation into astable, synthetic resin binder composition.

The amount of excess ammonium hydroxide used in the preparation of themetal ammine complex coordi- 8 nation compound varies widely and dependsupon many factors such as: the type of resin, thickener, and surfactantused; the degree of stability desired in the binder composition; thedegree of migrational control required; the degree of the subsequentwater dilution; etc. Under some circumstances, the excess of ammonia inthe metal ammine complex coordination compound solution may be as low asabout 20% on a stoichiometric or molar basis and may be as high as about100% excess, or even higher, as desired or required.

One typical preparation of a metal ammine complex coordination compoundis as follows:

1740 grams of zinc chloride solution is slowly dripped into 4620milliliters of concentrated ammonium hydroxide (28% NH,) with stirring,while the solution is surrounded by flowing, cooling water. The zinctetrammine chloride metal coordination complex forms at once. The zinccontent in the solution is approximately l0%. The reaction is believedto be as follows:

The quantities of zinc chloride and ammonia used herein are 8.94 molesand 68.6 moles, respectively. Inasmuch as four moles of ammonia arerequired for each mole of zinc chloride, 35.76 moles of ammonia arerequired to react with the 8.94 moles of zinc chloride. This leaves anexcess of 32.84 moles of ammonia in the reaction solution. As a result,the solution of zinc tetrammine chloride metal coordination complex isstrongly ammoniacal and stable. lts pH is approximately 10.

A formulated binder composition containing a resin latex, the zinctetrammine chloride, a polymeric carboxylic thickener, and the usualanti-foam agents, pigments, etc., handles normally and easily until themoment it is applied to the soaked, wet, fibrous web. At that moment ofdilution, the binder thickens suddenly and greatly, or actuallycoagulates, thus freezing it in place with substantially no furthermigration or lateral spreading.

It is believed that, prior to the dilution with water, there is a stablezinc ammine cation [Zn(NH in solution and that this stable cation has noeffect on the other constituents in the binder composition. However,when dilution takes place and the water phase is increased, theequilibrium in the preceding reaction shifts to the left with theformation of the zinc cation (Zn*), or its hydrated equivalent. It isbelieved that this zinc cation reacts with the carboxylic thickener,causing the formation of an insoluble polymeric gel. In some way, thisinsoluble precipitated polymeric gel destabilizes the latex. And, ofcourse, the reaction is generally similar between the cation and thesurfactant, if it is of the anoinic type, and/or the resin binderitself, if it contains carboxyl, or other reaction groups, as describedherein.

As defined herein, a metal ammine complex coordination compound is oneof a number of types of metal complex compounds, usually made byaddition of organic or inorganic atoms or groups such as ammonia (NH;,)to simple inorganic compounds containing the metal atom. Coordinationcompounds are therefore essentially compounds to which atoms or groupsare added beyond the number possible of explanation on the basis ofelectrovalent linkages, or the usual covalent linkages, wherein each ofthe two atoms linked donate one electron to form the duplet. in the caseof the coordination compounds, the coordinated atoms or groups arelinked to the atoms of the coordination compound, usually by coordinatevalences, in which both the electrons in the bond are furnished by thelinked atoms of the coordinated group.

The colloidal synthetic resin, the water soluble polymeric carboxylicthickener and the metal ammine complex coordination compound existtogether in a stable emulsion form and normally do not agglomerate,coagulate or precipitate, as long as the stable concentration levels ofNH.,OH or degree of dilution are maintained.

Subsequently, however, when the emulsion is diluted with water to asufficiently low concentration of NH OH, the resin immediatelycoagulates and agglomerates in place with no further spreading,diffusion or migration.

It is believed that, when the emulsion is diluted sufficiently, themetalcation is released from the metal ammine complex coordinationcompound and immediately attacks or reacts with the water solublepolymeric carboxylic thickener causing the resin particles toagglomerate or coagulate.

It is also believed that the metal ammine complex coordination compounditself, as exemplified by tetrammine zinc chloride [Zn(NH ]Cl ionizes tothe divalent cation [Zn(l lH and two anions Cl, even in the presence ofhigh pH, ammoniacal, colloidal latex and water soluble, polymericcarboxylie thickener. Yet, this complex cation has no apparent orappreciable effect on the colloidal latex or on the water soluble,polymeric carboxylic thickener and specifically does not form aninsoluble precipitate with either of them, as might have been expected.

As stated heretofore, it is further believed that dilution or otherwisediminishing the ammonium hydroxide content or concentration of thecolloidal dispersion releases the Zn cation and this reacts with andinsolubilizes the polymeric carboxylic thickener. Unexpectedly, however,the insolubilization of the polymeric carboxylic thickener also causesthe colloidal latex itself to rapidly coagulate, even though thechemical reaction which takes place does not, insofar as is presentlyknown, directly involve the latex, or its emulsifying or stabilizingsystem, if non-ionic.

Furthermore, methods have been discovered, as described herein to varyand control this unexpected sequence of chemical and physical events soas to controllably deposit a colloidal latex on the surface of, or in,or throughout a porous fibrous substrate. This method, as stated herein,can be used to very great advantage in print-bonding nonwoven fabrics orother porous substrates or in controllably placing and depositinglatexes on a porous fibrous substrate or the like in the textile, paper,leather, and related industries.

It is also to be appreciated that, when the emulsion is dilutedsufficiently, the metal cation which is released from the metal amminecomplex coordination compound also is capable of attacking or reactingwith any other chemical compounds which are present and which possessanionic groups, particularly hydroxy, carboxy, sulfino, sulfo, and likeacid groups.

For example, the metal cation which is released immediately attacks asurfactant system which is anionic and contains surfactants such asalkyl aromatic sulfonic acids, alkyl sulfonic acids, the carboxylicacids, and other surfactants such as, for example, dodecyl benzenesulfonate, octyl benzene sulfonate, hyxyl benzene sulfonate, octadecylbenzene sulfonate, cetyl sulfonate, hexyl sulfonate, dodecyl sulfonate,octadecyl sulfonte, and the sodium and potassium fatty acid soapscontaining from 5 to 18 carbon atoms. Other anionic surfactants includesodium p-l-methyl alkyl benzene sulfonates in which the alkyl groupcontains from 10 to l6 carbon atoms, the sodium di-n-alkylsulfosuccinates in which the alkyl groups contain from 4 to 12 carbonatoms, the potassium n-alkyl mal onates in which the alkyl groupcontains from 8 to l8 carbon atoms, the po' tassium alkyltricarboxylates in which the alkyl group contains from 6 to 14 carbonatoms, the alkyl betaines in which the alkyl group contains from 6 to l4carbon atoms, the ether alcohol sulfates, sodium n-alkyl sulfates,containing from 6 to 18 carbon atoms, etc.

The amount of surfactant used may vary from about 0.1% to 5% by weightof the resin solids dependent on the type resin being polymerized andthe conditions under which it is polymerized.

The specific surfactant which is selected for use in the resincomposition does not relate to the essence of the invention. It ismerely necessary that it possess the necessary properties andcharacteristics to carry out its indicated function of stabilizing theresin composition prior to the time that coagulation and precipitationof the resin is required. Additionally, in the event that it is desiredthat the surfactant assist in or promote the coagulation andprecipitation function, then it must possess the necessary anionicgroups, as described hereinbefor e, which are capable of reaction due tothe presence of the metal cations released from the metal ammine complexcoordination compound.

Moreover, the present inventive concept is operative with resins whichhave non-ionic or even polyionic emulsifying or stabilizing systems. Thepresence of an anionic surfactant system may be helpful in thecontrolled coagulation procedures described herein but it is notnecessary or even especially advantageous in many cases.

The mechanism of instant agglomeration, coagulation and precipitation ofthe colloidal resin binder may therefore be triggered subsequent todilution by reaction of the metal cation with either the water soluble,polymeric carboxylic thickener or the anionic surfactant, or both.

The dilution may be effected in different ways in order to activate thereaction mechanism. For example, the porous or absorbent fibrousmaterial may be pretreated by being pre-wet with a sufficient quantityof an aqueous medium, preferably water, whereby the colloidal resincomposition immediately becomes sufficiently diluted. Or, if desired,the colloidal resin composition may be first printed on the porous orabsorbent fibrous material and then substantially immediately treatedwith the aqueous medium such as water to effect the dilution whereuponthe colloidal resin particles substantially immediately agglomerate orcoagulate in place with no further spreading, diffusion or migration.

It is believed that the coagulation and precipitation take place bydilution alone wherein the NH groups in the metal ammine complexcoordination compound break down and become NH,0H in the excess waterbeing carried by the fibrous web. By this reaction, the metal cationsare released, coagulating and precipitating the resin. The reaction isbelieved to be as follows:

Me(NH ),Y+xH O Me(cation)+xNl-l.,OH+Y(anion) wherein Me is a metal suchas disclosed herein, x is a whole number from 2 to 8 (and more commonly2,4 or 6), and Y is an anion such as chloride, iodide, bromide, sulfite,sulfate, nitrite, nitrate, carbonate, acetate, borate, phosphate,citrate, chlorate, oxalate, etc.

It is to be appreciated that Me and Y normally form compounds, theformation of which can be explained on the basis of electrovalentlinkages, or the usual covalent linkages, wherein each of the two atomslinked donate one electron to form the duplet.

It is believed that the addition of the water to the resin dispersioncauses the equilibrium of the reaction mechanism to shift to the rightwhereby the metallic cations are released to bring about the describedcoagulation and precipitation of the resin. Lesser amounts of watercause the equilibrium of the reaction mechanism to move to the leftfavoring the continued stability of the metal ammine complexcoordination compound and the resin dispersion.

The amount of the water applied to the fibrous web varies widely,depending upon many factors, the most important of which is the nature,concentration, properties and characteristics of the synthetic resin,the metal ammine complex coordination compound, and the surfactantsystem in which they are stabilized. Normally, the amount of waterapplied to the fibrous web is in the range of from about 140% to about280%, and preferably from about 160% to about 220%, based on the weightof the fibrous web being treated. Such amounts are controlled by the useof suitable conventional vacuum apparatus, nip-rolls, squeeze-rolls,etc.

The amount of water which is applied to the fibrous web prior to theprinting of the resin binder also affects the degree of controlexercised over the coagulation and migration. The greater the amount ofwater, the greater is the control and the more rapid is the coagulationand the less is the migration. On the other hand, the less the amount ofwater in the fibrous web, the less is the control exercised, the lessrapid is the coagulation, and the greater is the migration.

It is also to be realized that the greater the amount of water ofdilution, then the greater is the degree of penetration of the resinbinder into the fibrous web. And, the lesser the amount of water ofdilution, then the lesser is the degree of penetration of the resinbinder into the fibrous web.

The degree of coagulation may be lowered even more and the degree ofmigration may be increased by the inclusion in the pre-wetting water ofasmall amount of an alkaline or basic material such as ammoniumhydroxide. The pH remains alkaline, just as it does in other variationsof this invention, and the coagulation and precipitation are purely theresult of the dilution.

When printed on a pre-wetted fibrous web during the manufacture ofnonwoven fabrics, the total migration of the resin binder solids may bereduced to as little as about 50% or less beyond the originallydeposited area. in some instances, the migration is relativelynegligible. Normally, however, the increase in area of the resin bindersolids, even under the most adverse conditions, does not materiallyexceed about 200%. Such values are to be compared to increases in bindermigration of at least about 300% and up to about 800% when emulsionpolymerized resins are applied to fibrous porous absorbent sheetmaterials, unaided by the principles disclosed herein.

The concentration of the binder resin solids in the binder area iscorrespondingly increased when utilizing the principles of the presentinvention and is in the range of from about 50% by weight to about 120%by weight, and more normally from about 60% to about by weight, based onthe weight of the fibers in the binder area.

The invention will be further illustrated in greater detail by thefollowing specific examples. it should be understood, however, thatalthough these examples may describe in particular detail some of themore specific features of the invention, they are given primarily forpurposes of illustration and the invention in its broader aspects is notto be construed as limited thereto.

EXAMPLE I A fibrous card web weighing about 570 grains per square yardand comprising rayon fibers 1% denier and 1% inches in length isintermittently print bonded by the rotogravure process using an engravedroll having 6 horizontal wavy lines per inch. The width of each line asmeasured on the engraved roll is 0.024 inch.

The composition by weight of the resin binder formulation used for theintermittent print-bonding is:

1. 7 lbs. ofa 55% solids latex of Air Reduction Aircoflex 510, acopolymer of ethylene and vinyl acetate stabilized with a nonionicsurfactant 2. 2 lbs. of water 3. 1 lb. ofa 10% solution ofa thickeningagent, Rohm and Haas Acrysol 51, a copolymer of acrylic acid andacrylamide. M01. wt. 375,000 500,000

4. 50 m1. ofa 31% solution of zinc tetrammine chloride metalcoordination complex (sp. gr. 1.13) containing 10% zinc equivalent or17.5 grams zinc tetrammine chloride (actual).

Conventional chemical calculations, using the above values, willestablish that there is approximately 0.312 moles of excess ammonia inthe zinc tetrammine chloride solution which is equivalent to 0.069 molarammonia in the resin binder formulation (approximately 10 lbs. or 4.5liters) which indicates that there is 0.118% excess ammonia not tied upin the zinc ammine chloride complex.

The fibrous card web is pretreated or pre-moistened with a large amountof water to the extent of about 190% moisture based on the weight of thefibers in the web.

The extra dilution with water is sufficient by itself to upset thestability of the resin dispersion when applied to the web and itinstantly coagulates and precipitates on the very wet fibrous web. Theprinted web is then processed, dried and cured.

The width of the binder line in the finished product is about 0.054 inchwhich represents a controlled total migration of about The surfacecoverage of the binder is about 32.4%. The percent binder in the bondednonwoven fabric is about 17.4%. The concentration of binder in thebinder area is about 54%, based on the weight of the fibers therein.Such measurements are obtained by procedures which are described ingreater detail in copending patent application Ser. No. 65,880, filedAug. 21, 1970.

The resulting nonwoven fabric has excellent strength, excellentsoftness, drape and hand, and excellent crossresilience EXAMPLE II Theprocedures of Example I are followed substantially as set forth thereinwith the exception that 160 grams of American Cyanamid curing resinCYREZ 933, an aminoform melamine formaldehyde type externalcross-linking agent, is added to the formulation. The results are goodand are generally comparable to those obtained in Example I, except thatthis sample has improved wet-abrasion resistance and very good launderability. The resulting bonded nonwoven fabric also finds commercialacceptance.

EXAMPLE Ill The procedures of Example II are followed substantially asset forth therein with the exception that the ethylene-vinyl acetatecopolymer is replaced by 7 pounds of 46% solids latex of Goodrich 2671,a self cross-linking acrylic copolymer containing ethyle acrylate andacrylonitrile. The results are good and are generally comparable tothose obtained in Example 11. The resulting bonded nonwoven fabric alsofinds commercial acceptance.

EXAMPLE IV EXAMPLE V The procedures of Example I are followedsubstantially as set forth therein with the exception that theethylene-vinyl acetate copolymer is replaced by 7 pounds of a 46% solidslatex of Goodrich Geon 576, a plasticized polyvinyl chloride-lower alkylacrylate copolymer stabilized with an anionic surfactant. The resultsare good and are generally comparable to those obtained in Example Iexcept that this product has very good heat sealing properties. Theresulting bonded nonwoven fabric also finds commercial acceptance.

EXAMPLE VI The procedures of Example I are followed substantially as setforth therein with the exception that the ethylene-vinyl acetatecopolymer is replaced by 7 pounds of a 50% solids latex of Rohm and HaasPIA-8, a self cross-linking polyethyl acrylate copolymer stabilized witha non-ionic surfactant. The results are good and are generallycomparable to those obtained in Example I. The resulting bonded nonwovenfabric also finds commercial acceptance particularly as a wet wipingcloth.

EXAMPLE VII The procedures of Example 11 are followed substantially asset forth therein with the exception that the thickening agent is 1pound of a l'% solution of the sodium salt of HerculesCarboxymethylcellulose 7H3S, having a high degree of polymerization inexcess of about 1000, a high molecular weight in excess of about200,000, a high viscosity of 900-3,000 centipoises, maximum viscosity,1% solution, at 25 C., and a degree of carboxymethyl substitution in therange of from about 0.65 to about 0.85 D.S. The results are good and aregenerally comparable to those obtained in Example II. The resultingbonded nonwoven fabric also finds commercial acceptance.

EXAMPLE VIII The procedures of Example I] are followed substantially asset forth therein with the exception that the thickening agent is 1pound of a 9% solution of the sodium salt of HerculesCarboxymethylcellulose 7M, having a degree of polymerization in excessof 500, a medium molecular weight greater than about 70,000, a mediumviscosity 30-100 centipoises, maximum viscosity, 1% solution, 25C., anda degree of carboxymethyl substitution in the range of from about 0.65to about 0.85 D5. The results are good and are generally comparable tothose obtained in Example 11. The resulting bonded nonwoven fabric isalso commercially acceptable.

EXAMPLE IX EXAMPLE X The procedures of Example IX are followedsubstantially as set forth therein with the exception that 1 pound of a9% solution of the sodium salt of Hercules Carboxymethylcellulose 9M8having a molelcular weight of about 100,000 is used as the thickeningagent. The results are good and are generally similar to those obtainedin Example IX.

EXAMPLES XI AND XII The procedures of Example IX are followedsubstantially as set forth therein with the exception that the sodiumsalt of Hercules Carboxymethylcellulose 7M1 and 7H4 are used. 7M1 has amedium molecular weight, a medium carboxymethyl substitution of 0.650.85 D.S., and a low viscosity range in centipoises at 25 C. of 50 for a2% concentration. 7H4 has a high molecular weight, a mediumcarboxymethyl substitution of 0.65 0.85 D.S., and a high viscosity rangein centipoises at 25 C. of 2,500-4,500 for a 1% c0ncentration. Theresults are good and are generally comparable to those obtained inExample IX. The resulting bonded nonwoven fabric is acceptablecommercially.

EXAMPLE XIII The procedures of Example II are followed substantially asset forth therein with the exception that the thickener is the sodiumsalt of Hercules Carboxymethylcellulose 7L2, having a low molecularweight of about 45,000, a degree of polymerization of about 200, aviscosity range in centipoises at 25 C. of 18 maximum at 2%concentration. An effect is noted but the results are not sufficient asto be commercially warranted.

EXAMPLE XIV EXAMPLE XV The procedures of Example II are followedsubstantially as set forth therein with the exception that thethickening agent is 1 pound ofa 10% solution of the sodium salt ofGoodyear Carboset 514 polyacrylate copolymer. The results are good andare generally comparable to those set forth in Example II. The resultingbonded nonwoven fabric finds commercial acceptance.

EXAMPLE XVI The procedures of Example II are followed substantially asset forth therein with the exception that the thickening agent is 1pound ofa 10% solution ofa neutralized sodium salt of Rohm and HaasAcrysol A-5 polyacrylate homopolymer. The results are good and aregenerally comparable to those set forth in Example II. The resultingbonded nonwoven fabric finds commercial acceptance.

EXAMPLE XVII The procedures of Example II are followed substantially asset forth therein with the exception that the thickener is l pound of a5% solution of a sodium salt of Kelco Kelgin XL alginate water soluble,polymeric, carboxylic thickener. The results are good and are generallycomparable to those obtained in Example II. The resulting bondednonwoven fabric finds commercial acceptance.

EXAMPLES XVIII AND XIX The procedures of Example II are followedsubstantially as set forth therein with the exception that the 50milliliters of zinc tetrammine chloride is: (a) increased to 100milliliters; and (b) decreased to 35 milliliters. The results in bothcases are good and are generally comparable to those obtained in Example[I The resulting bonded nonwoven fabrics are commercially acceptable.

EXAMPLE XX The procedures of Example II are followed substantially asset forth therein with the exception that the volume of zinc tetramminechloride is increased from 50 milliliters to 100 milliliters and theamount of Acrysol 5i thickener is increased from 1 lb. to 1 /2 lbs. Theresults are good and are generally comparable to those obtained inExample II, except that it is noted that practically all of the resinbinder is on one face of the nonwoven fabric whereby it may be moreeasily plied to another fabric or to another material.

EXAMPLES XXI AND XXII The procedures of Example [I are followedsubstantially as set forth therein with the exception that the zinctetrammine chloride is replaced by an equivalent amount of: (a) zinctetrammine sulfate; (b) zinc tetrammine carbonate; and (c) copperdiammine acetate. The results in all three cases are good and aregenerally comparable to those obtained in Example II. The resultingbonded nonwoven fabrics find commercial acceptance.

EXAMPLE XXIII placed by succinic acid which is a dicarboxylic acid.

The results are not satisfactory and the use of succinic acid does notyield commercially acceptable products.

EXAMPLE XXIV The procedures described in Example I are followedsubstantially as set forth therein with the exception that: (l) thecarboxylic thickening agent (Acrysol 51) is omitted; and (2) thesynthetic resin latex (Aircoflex 5l0) is replaced by a 50% solidssynthetic resin latex of a terpolymer of 46% butadiene,.5l% styrene, and2%.itaconic acid. The zinc tetrammine chloride metal coordinationcomplex remains the same. The results are inferior to the resultsobtained in Example I. The resulting nonwoven fabric has excellentstrength but does not have good softness, drape and hand, orcrossresilience. At best, it is marginally commercially acceptable.

EXAMPLE XXV The procedures described in Example I are followedsubstantially as set forth therein with the exception that: (l)-thecarboxylic thickening agent (Acrysol 51) is omitted; and (2) thesynthetic resin latex (Aircoflex 510) is replaced by a 50% solidssynthetic resin latex of a terpolymer of 46% butadiene, 51% styrene, and2% acrylic acid. The zinc tetrammine chloride metal coordination complexremains the same. The results are inferior to the results obtained inExample I. The resulting nonwoven fabric has excellent strength but doesnot have good softness, drape and drape, or crossresilience. At best, itis marginally commercially acceptable.

EXAMPLE XXVI The procedures described in Example I are followedsubstantially as set forth therein with the exception that: (l) thecarboxylic thickening agent (Acrysol 51) is omitted; and (2) thesynthetic resin latex (Aircoflex 510) is replaced by a 50% solidssynthetic resin latex of a terpolymer of 46% butadiene, 51% styrene, anda 2% methacrylic acid. The zinc tetrammine chloride metal coordinationcomplex remains the same. The results are inferior to the resultsobtained in Example 1. The resulting nonwoven fabric has excellentstrength but does not have good softness, drape and hand, orcross-resilience. At best, it is marginally commercially acceptable.

EXAMPLE XXVII The procedures described in Example I are followedsubstantially as set forth therein with the exception that: (l) thesynthetiic resin latex (Aircoflex 510) is omitted; (2) the added wateris increased from 2 lbs. to 3 lbs.; and (3) 7 lbs. of a 10% solution ofthe carboxylic thickening agent (Acrysol 51) is used. The results areinferior to the results obtained in Example I, particularly insofar aswet strength is concerned. However, the dry strength, softness, drapeand hand are good. The resulting nonwoven fabric is commerciallyacceptable and can be used as a flushable, disposable facing for asanitary napkin.

Having now described the invention in specific detail and exemplifiedthe manner in which it may be carried into practice, it will be readilyapparent to those skilled in the art that innumerable variations,applications, and extensions of the basic principles involved may bemade without departing from its spirit and scope.

What is claimed is:

l. A colloidal synthetic resin binder composition for bonding a fibrousweb of overlapping, intersecting fibers which comprises: a stable,colloidal aqueous dispersion having an alkaline pH comprising: (1) fromabout 0. 1% to about 60% by weight on a solids basis of a colloidalsynthetic resin; (2) from about 0.05% by weight to about 7% by weight,based on the weight of and copper.

2. A colloidal synthetic resin composition for application undercontrolled migration conditions to porous, absorbent materials whichcomprises a stable, colloidal aqueous dispersion having an alkaline pHcomprising: (1) from about 0.1% to about by weight on a solids basis ofa colloidal synthetic resin; (2) from about 0.05% by weight to about 7%by weight. based on the weight of said colloidal synthetic resin of asodium salt of an alginate polymer as a water-soluble, polymericcarboxylic synthetic resin thickener; and (3) from about 0.01% by weightto about 5% by weight, based on the weight of said colloidal syntheticresin of a metal ammine complex coordination compound, having theformula Me (NH Y wherein Me is a metal, x is a whole number from 2 to 8,and Y is an anion, said metal being selected from the group consistingof chro- 32 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3, 5,7 5 Dated February 975 Inventg -(s) H. Drelich and 3.30m

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

T- In Column 2, line 2, "Creslan should read "Creslan" I '1 In Column 2,line 3, "Dynel should read "Dynel" In 6011mm 2, line #7, MASSLINN shouldres. "MASSLINN" In Column line 63, "water if carried" should read wateris carried Column 8, line 21, "hxm os [2M should read hmz onz fin Column10, line 1, "hyxyl" should read hexyl In Column 10, line 3, "sulfonte"should read sulfonate in Column 11, line 1, "H20 Me'ishould read H 62 MeIn Column 13, line 22, "ethyle" should read ethyl In Column 17, line 3,"synthetiic" should read synthetic In Column 17, lines l8l9,"applications, and extensions" should read applications, modifications,and extensions Signed and sealed this 10th day of June 1975'.

(SEAL) Attes'c:

c'. MARSHALL DANN RUTH C. MASON Commissioner of Patents AttestingOfficer and Trademarks

1. A COLLODIAL SYNTHETIC RESIN BINDER COMPOSITION FOR BONDING A FIBROUSWEB OF OVERLAPPING, INTERSECTING FIBERS WHICH COMPRISES: A STABLE,COLLODIAL AQUEOUS DISPERSION HAVING AN ALKALINE PH COMPRISING: (1) FROMABOUT 0.1% TO ABOUT 60% BY WEIGHT ON A SOLIDS BASIS OF A COLLOIDALSYNTHETIC RESIN; (2) FROM ABOUT 0.05% BY WEIGHT TO ABOUT 7% BY WEIGHT,BASED ON THE WEIGHT OF SAID COLLODIAL SYNTHETIC RESIN OF A SODIUM SALTOF AN ALGINATE POLYMER AS A WATER-SOLUBLE, POLYMERIC CARBOXYLICSYNTHETIC RESIN THICKENER; AND (3) FROM ABOUT 0.01% BY WEIGHT TO ABOUT5% BY WEIGHT, BASED ON THE WEIGHT OF SAID COLLODIAL SYNTHETIC RESIN OF AMETAL AMMINE COMPLEX COORDINATION COMPOUND, HAVING THE FORMULA ME(NH3)XY WHEREIN ME IS A METAL, X IS A WHOLE NUMBER FROM 2 TO 8, AND Y ISAN ANION, SAID METAL BEING SELECTED FROM THE GROUP CONSISTING OFCHROMIUM, NICKEL, ZINC, AND COPPER.
 2. A colloidal synthetic resincomposition for application under controlled migration conditions toporous, absorbent materials which comprises a stable, colloidal aqueousdispersion having an alkaline pH comprising: (1) from about 0.1% toabout 60% by weight on a solids basis of a colloidal synthetic resin;(2) from about 0.05% by weight to about 7% by weight, based on theweight of said colloidal synthetic resin of a sodium salt of an alginatepolymer as a water-soluble, polymeric carboxylic synthetic resinthickener; and (3) from about 0.01% by weight to about 5% by weight,based on the weight of said colloidal synthetic resin of a metal amminecomplex coordination compound, having the formula Me (NH3)x Y wherein Meis a metal, x is a whole number from 2 to 8, and Y is an anion, saidmetal being selected from the group consisting of chromium, nickel,zinc, and copper.